A portable jack is often stored in a vehicle to enable a driver to lift the vehicle to effect emergency repairs, for example, to change a tire. One popular type of jack for automobiles is the pantograph jack. Known pantograph jacks typically have four arms hinged in a parallelogram at four joints. One joint is located on a base of the jack. Another joint is positioned at a load rest vertically above the base. Two other free floating joints are located on a horizontal diagonal at opposite corners of the parallelogram formed by the arms. When the free floating joints are drawn together in a horizontal plane the arms extend vertically to lift the load support with respect to the base and vice versa. The relative position of the free floating j`oints is controlled by threaded drive shaft which links them together.
Modern jack design places increasing emphasis on low cost manufacture and light weight. Manufacturing costs may be reduced by reduction in material requirements and minimization of manufacturing and assembly steps. Reducing material requirements also reduces weight. The joints at the base and the load rest of a pantograph jack are typically made with pins. For example, the lower pantograph arms have ends with gear teeth which mesh within the base as the arms turn in opposite radial directions. To achieve this meshing and turning each lower end of the two arms is set to rotate on a pin in the base. Aligned holes penetrate each lower end and the base to receive a pin. Similar arrangements are made to connect the upper arms in the load rest. It is an object of this invention to simplify the construction of these joints to reduce costs and weight.